Pile shaft



L. MLLER May 28, 1963 PILE SHAFT 2 Sheets-Sheet 1 Original Filed Julyl2, 1955 L. MLLER PILE SHAFT May 28, 1963 2 Sheets-Sheet 2 OriginalFiled July l2, 1955 af www4/W @fron/vini United State# Patent O., i

3,091,090 PILE SHAFTV Ludwig Mller, 45 Wilhelmstrasse, Marburg (Lahn),Germany Original application July 12, 1955, Ser. No. 521,571, now PatentNo. 2,924,948, dated Feb. 16, 1960. Divided and this application Dec.21, 1959, Ser. No. 860,872

12 Claims. (Cl. 61-53) The invention relates to a pile shaft to bedriven into the ground such as a foundation pile, and more particularlyto a metal pile having at its leading end an apertured foot of widerperipheral outline than the pile shaft proper. This foot serves to lforma substantially annular space about the pile shaft during the ydrivingoperation by displacing and compressing `the penetrated ground strata.This space is gradually Ifilled =with cementitious material fed down thepile shaft and extruded therefrom through the foot apertures and lateralopenings in the pile shaft proper as the driving operation progressesthus forming a jacket about the pile shaft which anchors the same in theground.

The present application is a -divisional application divided out of mycopending application Serial No. 521,571 led July l2, 1955 and issued asPatent No. 2,924,948 on lFebruary `16, 1960.

lt is an object of the present invention to provide a novel and improvedpile shaft of the general kind above referred to, which combines asimplified and inexpensive construction with strong anchorage andloading strength.

Another object of the invention is to provide a novel and improved pileshaft design which affords the advantage of a substantial saving ofstructural material, generally steel or iron, Without a sacrifice in thestrength and loading capacity of the pile.

Still another and more specific object of the invention is to provide anovel and improved pile shaft structure in the form of an open frameworktied to a central driving shaft which also serves as a feed pipe or afeed pipe carrier for feeding cementitious material to iill theframework and to form the aforementioned jacket anchoring the pile inthe ground. With such pile structure, the driving force applied to thecentral pile shaft is transmitted to the framework as a downwardlydirected pulling force rather than as a bending strain. As an openframework has a far greater pulling strength than bending strength, theframework can be made comparatively light. This affords the advantage,in addition to the saving of material, of reduced weight whichfacilitates transport and erection of the pile shaft preparatory todriving.

A further object of the invention is to provide a novel and improvedpile shaft in the form of an open framework ywhich is gradually lledwith and jacketed by cementitious material as the driving operationprogresses thereby forming a solid pile shaft within the ground andtying the foot to the surrounding soil strata. The use of an openframework aords the further advantage that the components thereof can belongitudinally tensioned prior to lbeing embedded in the cementitiousmaterial whereby the pile shaft after hardening of the material has theproperties of prestressed reinforced concrete.

A still further object of the invention is to provide a novel andimproved pile shaft having clearing means 3,091,053@ Patented May 28,1953 2 along its length which impede the penetration of soil and stonesinto the interior of the pile shaft during the driving operation therebyassuring an unimpeded feed of cementitious material down the framework.

Other and further objects, features and advantages of the invention willbe pointed out hereinafter and set forth in the appended claims formingpart of the application. In the accompanying drawings, severalpreferredrem bodiments of the invention are shown by way of illustrationand not by way of limitation.

In the drawing:

FIG. l is a fragmentary elevational view, in section, of a pile shaftaccording to the invention.

FIG. 2 is a section taken on line II--II of FIG. l.

FIG. 3 is a section taken ou line III-III of lFIG. 1.

FIG. 4 is a section taken on line IV-IV of FIG. 1.

FIG. 5 is an elevational section of the leading end of the pile shaftand the pile foot, turned through in reference to FIG. 1.

FIG. 6 is :a section of a lfinished and anchored pile taken on lineVI-Vl of FIG. 7.

FIG. 7 is an elevational View of a driven pile shaft before feeding thecementitious material, and

FIG. 8 is a sectional view of a modification of the framework of thepile shaft.

Referring first to FIGS. 1 through 7 in detail, the exemplified pileshaft :according to these figures comprises an open framework formed offour angle bars 1 made of steel or iron. The angle bars are joined toand held in position by longitudinally spaced ring or sleeve members.24. The angle bars 1 are Xedly secured to the circumferential outsideWall of sleeves 24, generally by welding, to define a square peripheraloutline. The lowermost sleeve 24 mounts a generally wedge shaped pilefoot 3 fiXedly secured to the lowermost sleeve 274 as by welding. A flatchisel 2 protrudes from foot 3 strongly secured thereto, to facilitatesplitting of stones and other obstructions encountered during thedriving operation. The uppermost sleeve 24 is preferably substantiallylonger than the `other sleeves to accommodate a sealing collar 4.lCollar yd serves as a closure member to seal oif the hollow space 5formed by -foot 3 during the driving operation. Both the foot and thecollar have maximum peripheral outlines wider than the peripheraloutline of the pile shaft proper. The peripheral outline of the collaris preferably slightly wider than that of the foot. The upper end of theelongated sleeve 24 is preferably reinforced by means of a sleeve orcollar 6 welded to sleeve 24'.

The inside of lowermost sleeve 24 which protrudes into Ithe foot mountsa ring 17 upon whichA loosely rests a hollow shaft 18 to which thedriving force isv applied during the driving operation. Shaft 18 isslidable sleeves 24. It is made of suitable steel or iron andconstitutes a driving shaft.

The framework of the pile shaft formed by angle irons 1 and sleeves 24mounts a plurality of clearing lugs v12. These lugs are longitudinallyspaced and circumferentially staggered as can best be seen in FIG. 7.'Ihey preferably have a triangular cross section lengthwise of the pileshaft and serve yto clear and push aside loose soil and stones duringthe driving operation. In addition to lugs 12 similarly shaped lugs 19protrude laterally from foot 3. Lugs 19 impede' the penetration of soiland stones into the hollow foot 3 through lateral apertures 3a in thefoot. For the same purpose, the open top end of the foot is partlycovered by means of two angle flanges 20. As is shown in FIG. 1, theseangle flanges are longitudinally spaced from the top rim of the foot toleave peripheral apertures. Angle anges `20 prevent or `at least impedethe penetration of soil or stones into the foot om the top thereof.

During the driving operation, the pile driver strikes upon driving shaft1S. 'I'he resulting, longitudinally directed driving force is directlytransmitted to chisel 2 and foot 3 through shaft 18 and ring 17. As aresult, the framework for-med by the four angle bars 1 and joiningsleeves 24 is not subjected to longitudinal pressure and appreciablebending stresses, but is pulled down by the foot into the spacegradually formed by the foot about the framework formed by bars 1 andsleeves 24 as the driving operation progresses. In other words, theframework is subjected to tensional stresses only. After the drivingoperation has been completed or while the same is still in progress,hardening cementitious material such as concrete, in a state of Yfairlyhigh owability, is fed through shaft 17S, which Vnow serves as feedpipe, iirst into the hollow foot and then as shaft 18 is graduallyraised into the'framework itself and the hollow space 5 surrounding it.The concrete is preferably fed at high pressure whereby the penetratedstrata of soil are more or less compressed and the concrete will also beforced into the ground to a certain extent. As is apparent, the concretekeys itself in eifect into the ground thereby assuring a stronganchorage within the ground. Just before the completion of the drivingoperation, collar 4 will engage the ground at the surface level therebysealing space 5. Such sealing facilitates a pressure build-up ofconcrete within space 5 which in turn causes a stronger compression ofthe surrounding ground and the penetration of concrete into the ground.After the closure of space 5, the pressure of the concrete feed may befurther increased. Y

. While the sleeves 24 have been found to be suitable, bars 1 can alsobe Vjoined by means of .'wires, bands or strips made of suitable metalsuch as iron or steel which are wrapped helically around the bars andare secured to the bars, for instance by electric welding.

The bars 1 may be longitudinally tensionedV prior to the feeding of theconcrete by any of the many tensioning devices known and suitable forthe purpose. If pretensioningrof the bars'is intended, it is preferableto use comparatively thin bars or even heavy wires. AS is apparent, apile shaft formed of concrete reinforced by embedded pre-tensioned barswill have in effect the properties of pre-stressed concrete.

Instead of providing -a tubular driving shaft 18 and using such shaft asfeed pipe for the cementitious material, a solid driving shaft may alsobe used. Feed pipes must be'then provided along the lengths of the solidshaft. FIG. 8 shows such an arrangement. According to this figure, aprofiled bar in the form of a double T bar 25' Vis provided. Two feedpipes 26 extend along the web of said bar and are preferably suitablysecured to the web.l The pile shaft structure of FIG. 8 is otherwise thesame as previously described. t

While the invention hasV been described in detail with respect Vtocertain now preferredk examples and embodiments of the invention it willbe understood by those skilled in the art after understanding theinvention, that various changes and modifications may be made withoutdeparting from the spirit and scope of the invention, and it isintended, therefore, to cover `all such changes and modifications in theappended claims.

What is claimed as new and desired to be Secured by Letters Patent is: Y

1. A prefabricated pile shaft for driving into the ground to bepermanently anchored therein, said pile shaft comprising severallengthwise parallel rigid bars disposed to r means iixedly secured tosaid bars for securing the same in said generally tubular relationship,a hollow foot having a peripheral outline wider than the maximumperipheral outline of said framework iixedly secured to the leading endof the framework in alignment therewith, an abutment member securedwithin said framework at the end thereof secured to the foot, and anelongated pile driving member for driving the pile shaft into theground, said driving member extending into said framework from thetrailing end thereof slidable in reference to the framework and abutting-with its leading end upon said abutment member whereby a longitudinallydirected driving force applied to the trailing end of the driving memberis transmitted by said member directly to the leading end of theframework and to the foot secured thereto to exert a downwardly directedpulling force at said leading end of the framework.

42. A pile shaft according to claim l wherein said joining means are inthe form of several longitudinally spaced, generally sleeve shapedmembers, and wherein said abutment member is in the form of a generallyring shaped member secured within the lowermost sleeve member in coaxialalignment with said sleeve members, the outer wall of said lowermostsleeve member being secured to said foot and the leading end of saidpile driving member resting upon the trailing edge of said ring member.

3. A pile shaft according to claim 1 wherein said pile driving member isin the form of a tube open at its inner end for feeding cementitiousmaterial into said framework and foot by raising the tube inY referenceto the framework during the feeding of material.

4. A pile shaft according to claim 1 wherein said pile driving member isin the form of a profiled bar having a web, and a feed pipe extendsalong the length of the web of said bar secured thereto for feedingcementitious material into said framework `and foot, said profiled barbeing axially slidable within the framework for raising the bar and thepipe in reference to the framework during the feeding of material.

5. A pile shaft according to claim l wherein lugs forY 6. A pile shaftaccording to claim 1 wherein said foot Y has side walls includingapertures, and wherein hollow lugs having lateral openings are securedon said side walls to cover said apertures for impeding ingress oflooseV ground into the foot.

7. A pile shaft according to claim 5 wherein said lugs have a triangularcrossrsection longitudinally of the bars.

V8. A pile shaft according to claim 4 wherein said proled driving bar isa double T bar.

9. A prefabricated pile shaft for driving into the ground to bepermanently anchored therein, said pile shaft comprising an open metalframework composed of several bars and several sleeve members, said barsbeing iixedly secured to the outside wall of said sleeve members inparallel and circumferentially spaced relationship, said sleeve membersbeing spacedV lengthwise of the bars, a foot having a peripheral outlinewider than the maximum peripheral outline of said framework ixedlysecured to the leading end of the framework and in alignment therewith,an abutment member iixedly secured within the lowermost sleeve, and anelongated pile driving member extending within said sleeve members fromthe trailing end of said framework slidable in lreference thereto andabutting with its leading end against said abutment member whereby adriving force longitudinally applied to the trailing end of said drivingmember is transmitted by said member directly to the leading end of saidframework and the foot secured thereto to exert a downwardly directedpulling force upon said leading end of the framework. f

10. A pile shaft according to claim 9 whereinV said bars 5 6 are in theform of angle -bars secured with their longitu- References Cited in thefile of this patent dinal ange edges to said sleeve members to define anUNITED STATES PATENTS outer substantially rectangular outline of theframework.

th 1 t 1 b '11 th `t. 1n e Owermos s eeve mem er coaxra y erewih2,875,584 Turziuo Mar. 3, 1959

1. A PREFABRICATED PILE SHAFT FOR DRIVING INTO THE GROUND TO BEPERMANENTLY ANCHORED THEREIN, SAID PILE SHAFT COMPRISING SEVERALLENGTHWISE PARALLEL RIGID BARS DISPOSED TO DEFINE A GENERALLY TUBULAROPEN METAL FRAMEWORK, JOINING MEANS FIXEDLY SECURED TO SAID BARS FORSECURING THE SAME IN SAID GENERALLY TUBULAR RELATIONSHIP, A HOLLOW FOOTHAVING A PERIPHERAL OUTLINE WIDER THAN THE MAXIMUM PERIPHERAL OUTLINE OFSAID FRAMEWORK FIXEDLY SECURED TO THE LEADING END OF THE FRAMEWORK INALIGNMENT THEREWITH, AN ABUTMENT MEMBER SECURED WITHIN SAID FRAMEWORK ATTHE END THEREOF SECURED TO THE FOOT, AND AN ELONGATED PILE DRIVINGMEMBER FOR DRIVING THE PILE SHAFT INTO THE GROUND, SAID DRIVING MEMBEREXTENDING INTO SAID FRAMEWORK FROM THE TRAILING END THEREOF SLIDABLE INREFERENCE TO THE FRAMEWORK AND ABUTTING WITH ITS LEADING END UPON SAIDABUTMENT MEMBER WHEREBY A LONGITUDINALLY DIRECTED DRIVING FORCE APPLIEDTO THE TRAILING END OF THE DRIVING MEMBER IS TRANSMITTED BY SAID MEMBERDIRECTLY TO THE LEADING END OF THE FRAMEWORK AND TO THE FOOT SECUREDTHERETO TO EXERT